Mascara products are very popular. Today, the best selling mascara products have department store sales between one and five million dollars per year in the United States alone. Because of this, significant resources are devoted to the development of innovative mascara products. Innovative mascara products are those that introduce new features to the consumer or that improve upon exiting mascaras by making them perform better or by making them less expensive. Innovation in mascara products may occur in the composition or in the applicator used to apply the composition. Being innovative in the field of mascara products can be a challenge because mascara compositions are one of the most difficult cosmetics to formulate, package and apply. In part, this is owing to the physical and rheological nature of the product. Mascara is a heavy, viscous, sticky and often messy product. It does not flow easily in manufacture, filling or application, while drying out quickly at ambient conditions. It may contain volatile components that make safety in manufacture an issue. Mascara is also difficult because of the target area of application. The eyelashes offer a very small application area, while being soft, flexible, delicate and in close proximity to very sensitive eye tissue. Being flexible, the eyelashes yield easily under the pressure of a mascara applicator which makes transfer of the product onto the lashes difficult. The act of transferring a rheologically difficult product to a small, delicate target, and in so doing, achieve specific visual effects, is the challenging task of mascara application. Furthermore, mascara is unlike most cosmetic products because more than most cosmetics, the success of a mascara product depends on using the product with the right applicator. The overall consumer experience depends on both the product and on the applicator used to apply it. A well executed mascara formulation may prove to be a failure in the marketplace if not sold with the right applicator to apply and work the mascara onto the lashes, to achieve the desired effect. Taken the other way, not every mascara composition is right for every kind of mascara applicator. Therefore, a mascara product that is sold with an otherwise commercially popular applicator, may not be well received by the consuming public, if the mascara composition does not complement the applicator function. For this reason, early in development, mascara formulators should and do consider what type of applicator will best complement their composition or what type of composition will benefit the most from a particular applicator. The present application is concerned with the question: given a vibrating applicator, which types of mascaras give the best performance and most benefits?
Prior to U.S. Ser. No. 11/154,623 (hereinafter, the “Kress application”), there may have been very little disclosure in the prior art concerning which type of mascara compositions work better with which types of applicator. By “work better” we mean that one or more art-recognized properties of mascara application is improved by choosing a particular kind of mascara for use with a particular kind of applicator, compared to the same mascara with some other applicator or a rheologically different mascara with the same applicator. Specifically, applicants were unaware of any disclosure concerning which types of mascara compositions would benefit from use with a vibrating applicator. For the vast majority of mascara products on the market, no mechanism is provided to alter the rheological and application properties of the mascara at the time of application.
U.S. Pat. No. 5,180,241 describes a mascara container and conventional mascara brush wherein the container includes a helical spring on the inside of the container, through which the brush must pass on its way out of the container. The product on the brush is said to have its thixotropy broken by the action of the loaded bristles flexing and straightening as they squeeze through the turns of the spring. The reference does not quantify in any way to what degree the viscosity is affected nor how long the effect lasts. Disadvantages of this system include the fact that the mascara is only sheared for a moment while the brush is passing through the spring. There is no mechanism for longer, continuous shearing for an extended period of time, several seconds or minutes. There is no shearing after the brush is removed from the container, for example, while the mascara is being applied to the lashes. During this time, the viscosity, to the extent that it may have been reduced, is building back to its original value, so that the full, if any, advantage is not even realized. If a user attempts to increase the amount of shearing by repeatedly pumping the applicator through the spring, this will have the detrimental effect of incorporating air into the product and drying it out. This would actually produce a result opposite to that intended, causing the product to thicken and flow less well. Also, in this reference there is no mention of mascaras that are capable of anti-thixotropic behavior (or thickening when sheared) and no suggestion of how this system may affect future mascara formulations. This is unlike the present invention wherein the viscosity is substantially, measurably altered by shearing, the duration of which is controllable by the user and which duration may be several seconds or minutes. Pumping the applicator is not necessary to cause shearing and anti-thixotropic mascaras can benefit from the present invention as well as thixotropic. Also, the present invention opens the way for changes in the way mascaras are conventionally formulated.
In U.S. Pat. No. 5,775,344, the mascara product is heated just prior to and/or during application. Generally, heat is supplied by a heating element powered by a battery. The heating element may be in the container that holds the mascara or in the brush that is dipped into the mascara. The '344 patent discloses cosmetic product devices that heat the entire contents of a reservoir prior to an application, each time this device is used. But it should be appreciated that not all mascaras can be temperature cycled without damaging the product. For mascaras that will be changed structurally or chemically by the application of too much heat or from being too often heated, these devices are wholly unsuitable. This is unlike the present invention, wherein the product remaining in the reservoir is not heated and remains in good condition for future use. Another disadvantage of these devices is the need for thermal insulation to keep the heat inside the reservoir. The insulation makes these devices more complex and costly than the present invention, wherein the reservoir is neither heated nor insulated.
Since the Kress application, it is clear that a vibrating mascara applicator having a vibrational frequency from about 10 to about 1000 cycles per second, can have a substantial persisting rheological effect on a mascara composition (as the term “persisting rheological effect” is defined in the Kress application). Thus, since the Kress application, a mascara composition's response to vibration (i.e. its rheological profile) has taken on a much greater significance to the expert mascara formulator.
A thorough discussion of the measurement of rheological profile and the response of mascara to a vibrating applicator, can be found in the Kress application. A thorough discussion of mascara brush characteristics and mascara brush performance can be found in the Kress application. Also, a thorough discussion of prior art motion mascara brushes and other electric brush devices can be found in the Kress application.
Mascara Compositions: Typical Components
Turning now, to mascara compositions, conventional mascara formulations include oil-in-water emulsion mascaras which may typically have an oil phase to water ratio of 1:7 to 1:3. These mascaras offer the benefits of good stability, wet application and easy removal with water, they are relatively inexpensive to make, a wide array of polymers may be used in them and they are compatible with most plastic packaging. On the down side, oil-in-water mascaras do not stand up well to exposure of water and humidity. Oil-in-water mascaras are typically comprised of emulsifiers, polymers, waxes, fillers, pigments and preservatives. Some polymers behave as film formers and improve the wear of the mascara. Some polymers affect the dry-time, rheology (i.e. viscosity), flexibility, flake-resistance and water-proofness of the mascara. Waxes also have a dramatic impact on the rheological properties of the mascara and will generally be chosen for their melt point characteristics and their viscosity. Inert fillers are sometimes used to control the viscosity of the formula and the volume and length of the lashes that may be achieved. Amongst pigments, black iron oxide is foremost in mascara formulation, while non-iron oxide pigments for achieving vibrant colors has also become important recently. Preservatives are virtually always required in saleable mascara products.
There are also water-in-oil mascaras whose principle benefit is water resistance and long wearability. These mascaras may typically have an oil phase to water ratio of 1:2 to 9:1. Various draw-backs of water-in-oil mascaras may include: difficulty in removing the product from the lashes, a long dry-time, a high degree of weight loss from the product reservoir, generally less compatibility with packaging materials than oil-in-water mascaras and a relatively low flash point. Water-in-oil mascaras are typically comprised of emulsifiers, waxes, solvents, polymers and pigments. Volatile solvents facilitate drying of the mascara. Polymers play a similar role in water-in-oil mascaras as in oil-in-water discussed above, although in the former, an oil miscible film forming polymer is recommended. The same classes of pigments may be used in water-in-oil mascaras, as in oil-in-water. Here though, a hydrophobically treated pigment may provide improved stability and compatibility.
The more common mascara formulations comprise one or more waxes, which provide all or the most significant portion of a mascara's structure, although polymer's may also act as structuring agents. This is true whether the mascara is oil-in-water or water-in-oil. In recent years, gel mascaras or gel-based mascaras have gained popularity. Gel mascaras may also be oil-in-water or water-in-oil emulsions, or non-emulsions, and in general, one or more gelling agents are added to a water or oil phase. The gel network is able to provide significant structure to the mascara, so that a reduced amount of wax, sometimes no wax, is needed. The gel network is so efficient at creating structure, that gel-based mascaras and wax-based mascara typically have comparable order of magnitude viscosities. A non-exhaustive list of gellants which may be used as structuring agents in the production of gel-based mascaras includes:
Water phase—sodium polymethacrylate, sodium polyacrylate, polyacrylate, polyacrylate copolymers, ammonium acrylodimethyl taurate/VP copolymer, ammonium acrylodimethyl taurate/beheneth 25 methacrylate crosspolymer, acrylates/C10-30 akyl acrylates crosspolymer, carbomer, polyquaternium, carrageenan;
Oil phase—VP/eicosene copolymers, polyisobutene, polypropylene, polyethylene, polyurethane, ethyl cellulose, bentonite, dextrin palmitate, stearoyl, inulin, dibutyl lauroyl glutamide, dibutyl ethylhexanoyl glutamide, rosinates and resoinate derivatives, polyamides and derivatives;
Gums—xanthan gum, cellulose, carboxymethylcellulose, hydroxyethylcellulose, agar, starch, tapioca starch, clays, (kaolin, bentonite), PVP.
Mascara Compositions: Characteristics
There is an established vocabulary for discussing the performance characteristics of mascara. Each of these characteristics can be evaluated and assigned a number on a random scale, from 0 to 10, say, for purposes of comparison during formulation. “Clumping”, as a result of mascara application, is the aggregation of several lashes into a thick, rough-edged shaft. Clumping reduces individual lash definition and is generally not desirable. “Curl” is the degree to which a mascara causes upward arching of the lashes relative to the untreated lashes. Curl is often desirable. “Flaking” refers to pieces of mascara coming off the lashes after defined hours of wear. The better quality mascaras do not flake. “Fullness” depends on the volume of the lashes and the space the between them, where “sparse” (or less full) means there are relatively fewer lashes and relatively larger separation between the lashes and “dense” (or more full) means the lashes are tightly packed with little measurable space between adjacent lashes. “Length” is the dimension of the lash from the free tip to its point of insertion in the skin. Increasing length is frequently a goal of mascara application. “Separation” is the non-aggregation of lashes so that each individual lash is well defined. Good separation is one of the desired effects of mascara application. “Smudging” is the propensity for mascara to smear after defined hours of wear, when contacting the skin or other surface. Smearing is facilitated by the mascara mixing with moisture and/or oil from the skin or environment. “Spiking” is the tendency for the tips of individual lashes to fuse, creating a triangular shaped cluster, usually undesirable. “Thickness” is the diameter of an individual lash, which may be altered in appearance by the application of mascara. Increasing thickness is usually a goal of mascara application. “Wear” is the visual impact of a mascara on the lashes after defined hours as compared to immediately after application. “Overall look” is one overall score that factors in all the above definitions. It is a subjective judgment comparing treated and untreated lashes or comparing the aesthetic appeal of one mascara to another. The ideal mascara will possess all of the desirable properties while avoiding the undesirable.
While all of the mascara characteristics mentioned above are useful and may be important to the mascara formulator, fullness, clumping and separation are usually strongly correlated with each other. While clumping is an undesirable property of mascara, it has historically been difficult to achieve fullness without some amount of clumping. That's is to say, fullness and clumping have a direct correlation. However, clumping is contrary to lash separation, so fullness and lash separation have usually had an inverse relationship. Thus, the art of conventional mascara formulation is a balancing act between separation and fullness, between too much of one and not enough of the other. One of the advantages of the present invention is that the inverse relationship between fullness and separation is corrected, so that both may be increased simultaneously.
Often, the formulator is interested in achieving thicker, fuller, well separated lashes. Characteristics like clumping and spiking tend to work against this, and a developer can improve one or more characteristics only at the expense of others. For example, to increase the fullness of a particular mascara, conventional wisdom suggests adding more structure to the composition. Conventionally, this means adding solids and semi-solids, such as waxes and fillers, to the mascara composition. However, one disadvantage of doing this is that it tends to increase the viscosity and clumping of the composition and decrease the user's ability to separate the lashes. A high level of solids and semi-solids can also create a negative sensorial effect because the high viscosity makes the mascara difficult to spread over the lashes. The result can be tugging on the lashes, discomfort associated therewith and a poor application. Furthermore, in recent years, structure has sometimes been added to mascara compositions by the use of one or more gellants. Gellants are able to provide structure that enhances fullness. However, the response of gel-type mascaras to a vibrating applicator is not likely to be the same as the response of wax-based mascaras. Certainly, this difference in behavior has not been contemplated or exploited in the prior art.
Virtually all mascaras can, if shearing means are provided, exhibit some degree of thinning or thickening behavior. With a non-vibrating brush, a user cannot significantly shear a mascara to cause it to exhibit its thinning or thickening behavior. Even if some alteration of the product's viscosity did occur as a result of a conventional applicator shearing the product in the container, the amount would be insignificant as compared to an applicator according to the Kress application, and no significant advantage would accrue to the user. To the best of the applicant's knowledge, the prior art does not identify or suggest which types of mascara compositions are best suited for use with a vibrating brush.
Throughout the specification, “static” or “at rest” mascara refers to mascara not subject to applied shear, so that the mascara is at rest, internally. For example, after a mascara has been applied to the lashes, it is static or at rest. While the mascara is being applied with a vibrating applicator, the mascara is undergoing shear, and is not “static” or “at rest”.
In terms of a vibrating applicator, it would sometimes be ideal to increase the structure of a mascara when the mascara is at rest (thus, increasing fullness), while minimizing the increase in viscosity of the mascara, when the mascara is undergoing shear. At other times, it may be ideal to increase structure when the mascara is undergoing shear (thus, increasing fullness) and retaining that structure in the mascara after the mascara is at rest.
Also, with the introduction of the commercially feasible vibrating mascara brush, it is now desirable to identify which types of mascara display an unusually large decrease in viscosity when undergoing shear, but which rebuild structure when shear is removed. Such mascara are expected to score relatively highly on separation and fullness, with decreased clumping.
Another phenomenon that has come to light since the Kress application, is the effect of a vibrating applicator on some ingredients in a mascara formulation. A case in point is microspheres or spheroidal particles, which may conventionally be added to reduce viscosity and aid spreading a mascara evenly over a target surface. With a vibrating brush, a problem of the spheroids sliding over and not adhering to the lashes has been observed. In one embodiment of the present invention, this problem is addressed.
In recent years, the idea of creating an alignment of certain filler materials or particles, in a direction parallel to the length of the lashes, has been suggested as a means to achieve a superior mascara application. In US2008/0138138, it was noted that a vibrating applicator may “obtain a better orientation of said fibers”. The reference only address the response of fibers, and not other types of fillers or particles, such as mica and spheres.